1. Field of the Invention
The present invention relates to a ribbon cassette attached to a printing device, and more particularly to a ribbon cassette for preventing an operating mechanism of the printing device from operating in a printing operation when the cassette is not attached to the printing device.
2. Discussion of Related Art
Conventionally, an electric detector is used as a sensor for detecting whether a ribbon cassette is installed or not, and the detector is operated by an operating projection formed on the ribbon cassette. When the detector is not actuated by the operating projection of the ribbon cassette, that is, when it is detected that the ribbon cassette is not attached, a control signal is applied for inhibiting a printing operation.
However, a carriage with the ribbon cassette attached thereon reciprocates along a printing line of a printing sheet and a control device for controlling the printing apparatus is placed on a circuit board fixed on a frame. Therefore, an electric wire has to be connected with the detector on the movable carriage and the circuit board so that wiring becomes complicated. The control device also has to provide an input port to input a detecting signal outputted from the detector so that the number of functions of the control device is limited. Further, the control device has to be always detecting the condition of the input port whether the detecting signal is input or searching the input port in interruption handling, so that a control program becomes more complicated and a program memory has to be increased. Accordingly, apart from adapting a construction of the ribbon cassette to a printing device employing a detector, the detector has other disadvantageous influences for a printing device by adding a very difficult design condition and increasing a product cost.